Analgesic actions of N-arachidonoyl-serotonin, a fatty acid amide hydrolase inhibitor with antagonistic activity at vanilloid TRPV1 receptors

Short- and long-term plasticity of the endocannabinoid system in neuropsychiatric and neurological disorders

The activity of the endocannabinoid system, in terms of the levels of the endocannabinoids and of cannabinoid receptors, or of the functional coupling of the latter to a biological response, undergoes to remodelling during pathological conditions. In the CNS, these changes, depending also on the nature of the disorder, can be transient or long-lasting, occur only in those tissues involved in the pathological condition and usually aim at restoring the physiological homeostasis by reducing excitotoxicity, inflammation and neuronal death. However, during chronic disorders, prolonged activation of the endocannabinoid system might also contribute to the symptoms of the pathology. Whilst acute changes of the tissue levels of the endocannabinoids reflect the "on demand" nature of their biosynthesis and release, and hence are effected mostly through regulation of the biosynthetic enzymes, chronic changes seem to be mostly due to longer-lasting alterations in the expression of anabolic and catabolic enzymes. The possibility of obtaining therapeutic advantage from endocannabinoid plasticity in neuropsychiatric and neurological disorders is discussed in this review article.

Symptom-related changes of endocannabinoid and palmitoylethanolamide levels in brain areas of R6/2 mice, a transgenic model of Huntington's disease

Previous studies have shown an impairment of the endocannabinoid system in experimental models of Huntington's disease. In transgenic R6/2 mice, created by inserting exon 1 of the human IT15 mutant gene into the mouse, and exhibiting 150 CAG repeats as well as signs of HD, a progressive decline of CB(1) receptor expression and an abnormal sensitivity to CB(1) receptor stimulation have been reported. Here, by using isotope-dilution liquid chromatography-mass spectrometry, we investigated whether the levels of three endogenous neuroprotective substances, the endocannabinoids anandamide (AEA) and 2-arachidonoylglycerol (2-AG), and palmitoylethanolamide (PEA), are altered in different brain areas of transgenic R6/2 versus wild-type (WT) mice at two different disease phases, i.e. in pre-symptomatic (4.5 weeks) or overtly symptomatic (10 weeks) R6/2 mice versus age-matched WT mice (n=4/group). Except for a approximately 25% decrease in 2-AG levels in the cortex, no significant changes in endocannabinoid and PEA levels were observed in pre-symptomatic R6/2 versus WT mice. By contrast, in symptomatic R6/2 mice the levels of all three compounds were significantly (approximately 30-60%) decreased in the striatum, whereas little changes were observed in the hippocampus, and a approximately 28% decrease of 2-AG levels, accompanied by a approximately 50% increase of AEA levels, was found in the cortex. These findings show that endocannabinoid levels change in a disease phase- and region-specific way in the brain of R6/2 mice and indicate that an impaired endocannabinoid system is a hallmark of symptomatic HD, thus suggesting that drugs inhibiting endocannabinoid degradation might be used to treat this disease.